As an alternative to performing more invasive medical procedures, many physicians are performing examinations and/or therapeutic procedures in vivo with catheters or other devices. Such devices are generally routed from outside the patient to an area of interest through a small opening in the skin or through a body orifice. Such devices often include one or more lumens by which additional tools, medicines, and the like, can be delivered to a site in order to perform a desired task.
In order to route a catheter to its desired location, many procedures require the use of a guidewire. The guidewire is first advanced by the physician to the point of interest and then left in place to serve as a rail over which additional devices can be routed in order to guide them to the desired location.
FIG. 1 shows an example of a conventional guidewire 10 and a catheter 20 positioned over the guidewire. In many procedures, it is desirable to leave the guidewire in place while one catheter is exchanged for another. Therefore, the proximal end 12 of the guidewire 10 is fixed while the catheter 20 is removed from the patient. In order to maintain a handle on the proximal end 12 of the guidewire 10, it is necessary that the portion of the guidewire that remains outside the patient be longer than the length of the catheter 20. Therefore, a catheter/guidewire system such as that shown in FIG. 1, requires the use of long guidewires that can be cumbersome to manipulate and can clutter an operating room.
To address the issues associated with changing catheters over long guidewires, many catheters include so-called “rapid exchange” lumens. As shown in FIG. 2, a rapid exchange catheter 30 includes an opening 32 on the sheath of a catheter and a slot 34 that extends along the length of the catheter through which a guidewire 40 can be pulled. To exchange the catheter 30 for another device while maintaining the position of the guidewire 40 in the body, the catheter 30 is stripped off the guidewire 40 by pulling it through the slot 34. A new catheter or device can be routed over the guidewire 40 by inserting the proximal end of the guidewire 40 into an opening of a guidewire lumen at the distal end of the new device and advanced such that the proximal end of the guidewire exits the opening 32. The opening 32 may be positioned towards the proximal end of the catheter or may be located more towards the distal end.
While rapid exchange catheters and devices have been developed for many procedures, they have not been adapted for use with steerable catheters or catheters that are required to transmit torque from the proximal to the distal end of the catheter. Such devices often include a wire braid to increase column strength and transfer rotational torque. However, cutting this braid to allow the removal of the guidewire results in the braid becoming unraveled or frayed in a manner that can compromise the construction and performance of the catheter.
Because steerable devices are becoming increasingly used to navigate through the patient's body, there is a need for a mechanism to incorporate the advantages of a rapid exchange guidewire lumen with devices that are steerable and/or can transmit torque.